Sediment filters are very important in well water applications, but are also used by those on municipal water. Sediment filters can act as a barrier against grit and particulates that can clog your water filter system, cause issues for household plumbing, and reduce the life of water-using appliances.
With a UV water filter system, sediment can reduce the efficacy by hindering the ability of UV light to reach the waterborne microorganisms. And if sediment is not filtered out before a whole-house water softener, sand or silt could enter the system and scratch and damage the fine-moving parts of the softener.